Neptune Help (page 2)

By — McGraw-Hill Professional
Updated on Sep 16, 2011


Neptune has a ring system similar to those of Uranus and Jupiter but fainter. These rings were revealed by the Voyager probe. The rings of Neptune are unique in the Solar System because the outermost one, called 1989N1R, is nonuniform. This name derives from the year of discovery (1989), the planet (Neptune), the ring number (1 means “outermost”), and R (which stands for “ring”).

Astronomers are not sure why 1989N1R is “clumped.” One theory holds that it was created only a little while ago, on a cosmic scale, possibly within the last few centuries. If an asteroid or comet ventured too close to the planet, it would break up because of gravitation. Eventually the particles would spread all the way around Neptune and form a uniform ring, but this process would require some time. Maybe it hasn’t had time to do this yet.

Another theory for the clumping of 1989N1R involves gravitational interaction between the ring particles and a tiny moon, Galatea . It is possible that certain gravitational resonances could cause the clumping.

The particles that make up the rings around Neptune are in general less than an inch in diameter. This was revealed by analyzing radio waves passing through or reflected from the particles. Large chunks of rock affect radio waves at medium and long wavelengths, and as the rocks become smaller, they affect radio waves at shorter wavelengths. Neptune’s rings were not detected when observations were made at radio wavelengths.

Practice problems of this concept can be found at: The Outer Planets Practice Problems

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